1. Field of the Invention
The present invention relates to an injector for providing fuel to one or more cylinders of an internal combustion engine.
2. Disclosure Information
Electromagnetically driven fuel injectors have been widely used in automotive internal combustion engines for many years. Such injectors typically rely upon an axially extending needle valve which is slidably mounted within the injector and which reciprocates each time the injector fires so as to meter the desired amount of fuel into the engine's cylinder or intake manifold. Conventional injectors can be quite noisy during operation. A more worrisome aspect of the conventional injector arises from the fact that alcohol blend fuels finding increasing acceptance in the marketplace are likely to attack such sliding surfaces, leaving behind corrosion which could impair the operation of the injector. Accordingly, it is one aspect of the present invention that an injector made according to this invention will not rely upon the sliding action of a needle to meter the desired amount of fuel and, as a result, such injector will be better able to withstand the effects of corrosion resulting from hostile fuels.
U.S. Pat. No. 2,881,980 to Beck et al. and U.S. Pat. No. 4,515,129 to Stettner disclose electromagnetically driven automotive fuel injectors in which the metering elements comprise relatively massive discs which must be reciprocated electromagnetically in order to meter the desired amount of fuel. Each of these injectors would be expected to suffer from inferior time response characteristics arising from the magnitude of the reciprocating masses.
U.S. Pat. No. 3,961,644 to Eckert and U.S. Pat. No. 4,763,635 to Ballhause et al. each disclose electromagnetically driven valves for use in automotive fuel systems. The '644 patent discloses a valve having a circular membrane clamped about its periphery and having a center section which contacts a valve seat. The valve disclosed in the '635 patent is intended to control the flow of vapors from an evaporative emission control system into the intake of an engine and includes a leaf spring with an attached armature, with the armature coming into sealing contact with the valve seat. Neither of these valves includes a flow control element having the degree of freedom and, hence, the time response characteristics, of an injector according to the present invention.
U.S. Pat. No. 3,751,001 to Rayment and U.S. Pat. No. 4,418,886 to Holzer disclose other types of electromagnetically operated valves which are not suitable for the high speed operation required of an internal combustion engine fuel injector. The '001 patent discloses a valve having a rotating disc which is moved into and out of sealing contact with a slot formed in one end of the valve housing. The '886 patent discloses a pilot valve operated device. Neither of these designs is practical for use in an engine fuel injector.
It is an object of the present invention to provide a fuel injector for an internal combustion engine having reduced operating noise as compared to conventional needle type injectors.
It is yet another object of the present invention to provide a fuel injector for an internal combustion engine having superior sealing characteristics to prevent after-injection, which may cause undesirable increases in engine exhaust emissions.
It is yet another object of the present invention to provide a fuel injector for an internal combustion engine having improved response time.
It is still another object of the present invention to provide a fuel injector for an internal combustion engine which is highly resistant to the corrosive effects of alcohol blended fuels.
It is an advantage of the present invention that an injector according to this invention may be manufactured with relative ease and at low cost.
Other objects, features and advantages of the present invention will become apparent to those reading this specification.